The present invention relates generally to wheel servicing machines. More particularly, this invention pertains to tire changing machines with bead removal arms configured for releasing a bead from its seated position on a wheel rim.
Conventionally, tire changing machines are equipped with a movable arm to engage and loosen the tire bead so that the tire can be removed from the wheel rim. Conventional bead removal arms typically include an arm that pivots relative to a machine base. A shoe is positioned on the arm to engage the tire sidewall to loosen the tire bead from the wheel rim. Conventional bead loosener arms are actuated using an actuator such as a powered pneumatic or hydraulic cylinder. An actuator rod extends from the base to the bead loosener arm.
The actuator rod may connect to the actuator rod at a pivoting joint. A conventional pivoting joint 130 is shown in FIG. 2 and FIG. 3. During use, an operator places a wheel and tire assembly in a space between the shoe 24 and the base 12. The operator controls the powered cylinder to retract the actuator rod 28. The actuator rod 28 extends through a pivot pin 132 on the bead loosener arm 20. The rod also includes a rod retainer 134 on the side of the pivot pin 132 opposite the machine base. During operation, the rod 28 pulls the bead loosener arm 20 toward the base 12, thereby causing the shoe to engage the side wall of the tire to loosen the tire bead.
In some conventional tire changing machines, the actuator rod 28 is slidable through a hole 136 in the pivot pin 132 in the bead loosener arm 20. When the actuator rod 28 is retracted toward the base, the retainer 134 engages the pivot pin 132, limiting the linear travel of the rod 28 relative to the bead loosener arm 20, causing the bead loosener arm 20 to be pulled toward the base in the direction of retraction of the actuator rod 28. As the bead loosener arm 20 is pulled toward the base 12, the shoe 24 eventually engages and depresses the side wall of the tire, causing the bead to be loosened from the wheel rim. After the bead has been loosened, an operator typically controls the powered cylinder to move the rod 28 back toward the bead loosener arm 20 to release the shoe from the tire side wall. This may cause the actuator rod 28 to slide through the hole 136. In such configurations, the user is required to manually pivot the bead loosener arm 20 away from the base.
One problem with conventional wheel servicing machines having bead loosener arms is that the bead loosener arm must be manually pivoted away from the base following a bead loosener operation. This can be burdensome for an operator. Another problem with conventional wheel servicing machines having bead loosener arms is that the actuator rod is coupled to the bead loosener arm at a pivoting joint having a limited range of angular motion. For example, as seen in the conventional embodiment in FIGS. 2-3, when rod 28 is pulled toward base 12, rod 28 is pivotable relative to bead loosener arm 20 in a substantially horizontal plane via the rotation of pivot pin 132 relative to bead loosener arm 20 in one angular direction. However, rod 28 is not pivotable relative to bead loosener arm 20 in any vertical plane. During use, the bead breaker arm 20 may encounter stress in a non-horizontal force vector, causing the bead loosener arm 20 to have a tendency to move in an upward or downward direction other than the substantially horizontal pull direction of rod 28. Such movement of the bead loosener arm puts strain on the actuator rod, the pivoting joint, and the actuator in conventional pivoting joints, such as those shown in FIGS. 2-3. The pivoting joint 130 in such conventional configurations does not allow the actuator rod 28 to pivot in a vertical plane relative to the bead loosener arm 20. Conventional bead loosener arm pivoting joints of this nature also fail to accommodate sag of the bead loosener arm in non-horizontal directions during extended use.
What is needed then are improvements in wheel servicing machines having bead loosener arms.